How to use a 540 motor with Lego Technic!

[Essge]

Hello. I hope this havent been posted here before :)

When 1 XL-motor is not enough, use 2, or 3, or 4 and so on.

I have stopped using XL-motors. They are too slow. I use buggymotors instead or just a 540 size brushed crawler motor.

Axial got 3 types of brushed motors. 20turn, 27turn and 55turn. The price is a lot lower than buying a Lego motor compared to the torque and speed.

I chose to use the 27turn.

The width of the mounting holes for 3mm screws fits perfectly with theese 2 cross blocks 2x1.

The pinion have 12 tooth. With a 36 tooth Lego gear, I get 3:1 ratio

This works great in the right truck. I dont think its very wise to use a lot of u-joints and cv-joints. Theese even break when using xl-motor.

For steering. I use a 9 grams servo hooked up to a PF-switch. Like this pic below.

I hope this can entertain you guys and gurls on the forum.

Let there be questions :D

Edited September 13, 2015 by Essge

[efferman]

you can edit your post

[Essge]

Alright, I will do that :)

Now you're happy efferman :D

Edited September 13, 2015 by Essge

[allanp]

I have a 540 size motor (not sure the exact one) in a tamiya king hauler. I'm pretty sure you can also find those motors in cheap cordless power tools, seriously powerful. You wanna use lubricant with something that big. Um, that sounded wrong!

[Essge]

Most of the brushed motors will work as long that you can fit the M1 pinion and a way to mount it to lego parts :)

[LEGO Train 12 Volts]

Nice tip!

[Brickthus]

OK, looks like 12-tooth mesh with 36-tooth LEGO cog would work reasonably well. Better have a supply of 36-tooth cogs for predicted wearout though! How well does the shape of the metal cog match the shape of a LEGO 12-tooth cog?

What is the typical speed and voltage for this motor? I expect faster than LEGO motors, which is good, but is it meant to be 9V or 12V for extended running?

What is the no-load speed of the 27-turn motor? Halving this value will give the optimum loaded speed, at which maximum electrical power is transferred to mechanical power.

I see you have an RC motor driver and battery pack. Might be too powerful for LEGO parts. What is a typical RS540 motor current (they usually go only by turns and not electrical parameters)? Would a LEGO LiPo motor driver be OK with the load? It is limited to 800mA output. I guess that means the current limit could keep it safe for the LEGO parts, so that only the 36-tooth cog would be prone to wearout?

What about motor heating? Is it too hot to touch, or too hot for the adjacent LEGO parts?

I think my old car tyre air compressor uses an RS540 motor, which would have been from a car 12V supply (up to 14.4V but low duty cycle as they are supposed to stop after inflating one tyre). It might be worth trying to liberate the motor to drive jet engine models! I did try harnessing a dremel-like drill but 135W was too much for LEGO models and at 10,000rpm it melted the axle! Hence the best alternative I have so far is 4x 47154 Technic motor at 4000rpm no-load (2000rpm loaded) using 1.3 Amps at 9.15V.

I also have a new compressor with a fridge motor for plenty of pneumatic power!

Mark

[Essge]

The shape of the cogs are almost the same.

The motor max input voltage is 8-cell NiMh 9.6 volts. I run 2s Lipo 7.4 volts. No-load current do I not know, but the esc can deliver up to 106A.

Try google "rs540 current" (etc). The you will find your answers :)

The motor can get hot, but a lego truck is not hard to make go forward.

I dont think the overpriced Lego Lipo can handle any 540 motor

Lego Lipo costs about $50. It is a 2s 1100mah.

A standard 2s 1300mah Lipo from a norwegian site called elefun.no costs about $15. Then you only need to make a cable to the PF-IR.

[aminnich]

I did the same thing with RC motors i had laying around, except I wasnt using crawler motors, i have using a Fuze 4200 Kv brushless motor with a LiPo battery setup..... Lets just say that the LEGO gear was basically melted and trashed. TOO MUCH POWER!!! :grin:

[GoldVillage]

Would not recomend regular RC motors for lego... even regular mabuchi and johnson 540 is about 16,000-18,000 rpm and 250-300 g-cm (at max eff) compared to 200-400 rpm and about 3,6 and 14 g-cm - which is the supposed torque for the m,l and xl motor (yes their listed data is probably wrong, it should be g-cm... not n-cm)

Edited September 16, 2015 by GoldVillage

[Essge]

Crawler motors works great if you take it slow. Lego melts when going fast

[Brickthus]

Looking at the Mabuchi Motor website:

An RS540 motor is too powerful for LEGO. 2.4A no-load current is prohibitive.

An RS-380PH motor would be better. Taking the 3270 version:

This has a 4.5-15V voltage range, nominal voltage 12V, ideal for the PWM range of PF with a bit to spare. (The nominal 6V of the 4045 version seems too low but could be tried as its maximum is 12V).

No-load speed is 16400rpm, so high efficiency at half that i.e. 8200rpm, just 4x the loaded speed of a 47154 Technic motor. In the speed range for a jet engine model but would need gearing otherwise.

No-load current = 0.37A, well-within PF LiPo capability. This would leave 0.43A for driving the model before the LiPo tripped its current limit.

2.28A at max efficiency needs a power supply but is possible (I use a dual 30V 3A bench power supply at home). Stall current of 14.0A would need heat management but I would never drive it that hard. Even my car tyre air compressor took only 6A to start and 4A steady load, driving pneumatic models; it heated the compressor outlet more than the motor.

13mNm at max efficiency, up to 95.2mNm stall torque compares to ~35mNm stall torque for LEGO motors i.e. nearly 3x the torque.

Output power up to 19.2W compares to 8W for a 12V train motor at 0.667A, so 2.5x the power of any previous LEGO motor. I used nearly 12W for one model so 19.2W is about right for the next step.

Fixing centres of 16.0mm would suit LEGO spacing. Not so sure on space for the right cog though. Would need a means of attaching to an axle.

It is useful to be able to run a model on safer low-power batteries because then a demo at work would not need extra safety tests. Might be possible to connect up 2x LiPos with diodes. I have used diodes with PF before, when matching gearmotors to train motors.

Mark

[PKW]

You should try To cut out a thermal cutoff from a BB and use V2 receiver if i remember right it can provide up to 2.1Amps (maximum for lego wires) maybe You'll have tp upgrade the receivers wire if Not using the lego servo motor because steering will drain lots of power

[GoldVillage]

Looking at the Mabuchi Motor website:

An RS540 motor is too powerful for LEGO. 2.4A no-load current is prohibitive.

An RS-380PH motor would be better. Taking the 3270 version:

This has a 4.5-15V voltage range, nominal voltage 12V, ideal for the PWM range of PF with a bit to spare. (The nominal 6V of the 4045 version seems too low but could be tried as its maximum is 12V).

No-load speed is 16400rpm, so high efficiency at half that i.e. 8200rpm, just 4x the loaded speed of a 47154 Technic motor. In the speed range for a jet engine model but would need gearing otherwise.

No-load current = 0.37A, well-within PF LiPo capability. This would leave 0.43A for driving the model before the LiPo tripped its current limit.

2.28A at max efficiency needs a power supply but is possible (I use a dual 30V 3A bench power supply at home). Stall current of 14.0A would need heat management but I would never drive it that hard. Even my car tyre air compressor took only 6A to start and 4A steady load, driving pneumatic models; it heated the compressor outlet more than the motor.

13mNm at max efficiency, up to 95.2mNm stall torque compares to ~35mNm stall torque for LEGO motors i.e. nearly 3x the torque.

Output power up to 19.2W compares to 8W for a 12V train motor at 0.667A, so 2.5x the power of any previous LEGO motor. I used nearly 12W for one model so 19.2W is about right for the next step.

Fixing centres of 16.0mm would suit LEGO spacing. Not so sure on space for the right cog though. Would need a means of attaching to an axle.

It is useful to be able to run a model on safer low-power batteries because then a demo at work would not need extra safety tests. Might be possible to connect up 2x LiPos with diodes. I have used diodes with PF before, when matching gearmotors to train motors.

Mark

Where you gettin the torque data from when it comes to the lego motors?

[RohanBeckett]

Where you gettin the torque data from when it comes to the lego motors?

the one... the only..... Philo!

http://www.philohome...s/motorcomp.htm

Edited September 17, 2015 by RohanBeckett

[nerdsforprez]

I have used RC motors alot. I think they can add power and fun even if they eat up Lego elements. Always use lubricant.

http://mocpages.com/moc.php/412797

[janssnet]

In case you're looking for more inspiration mounting a standard RC-motor to LEGO, please have a look at this video.

 

I'm using some of these constructions in an attempt to build a fast Hybrid LEGO car (combining standard RC-parts with LEGO). Things look very promising. Lots of speed, hardly wear-out of LEGO parts, great project. Aiming for 50+ km/h.

The RC-motor I'm using can be found here (21 turns, 20,000 RPM, 7.4V)

https://www.conrad.nl/nl/absima-thrust-b-spec-brushed-elektromotor-voor-autos-20000-omwmin-aantal-windingen-turns-21-239458.html

 

[New_User]

RS380 motor and those bigger ones are not lightweight and these motors are only threaded at the front end, not the back. Maybe we should also look into how to support the back end of the motor itself instead of letting the weight of the motor stressing the frontal mount.